Comparison RUCELF Stabik StAR-5000 5 kVA / 3500 W vs RUCELF SDWII-4000-L 4 kVA / 3000 W

— Relay. Such devices have a transformer with a set of contacts, each of which is responsible for a certain voltage value. Thus, the adjustment is carried out stepwise. And for switching between groups of contacts, a specialized relay is responsible, in full accordance with the name. Being simple and fairly inexpensive devices, relay regulators have high speed (see “Response speed”) and a wide input voltage range (see below). At the same time, the relay gives a rather large error (see "Output voltage accuracy") and is poorly adapted to work with high currents and sudden voltage surges (for example, when using a welding machine) — the contact group is highly likely to burn out. Therefore, models of this type are mostly designed for simple conditions where neither high accuracy nor power is required — for example, they are well suited for connecting individual household appliances. In addition, we note that the operation of the relay is often associated with a significant level of noise (primarily due to the characteristic "click"); this can cause serious inconvenience in residential use.

— Thyristor. The device of thyristor stabilizers is in many ways similar to the relay stabilizers described above: in particular, there is the same transformer with a set of separate outputs for step adjustment. However, switching between the windings is carried out not with the help of a relay, but with the help of...semiconductor devices — thyristors. The principle of their operation is also similar to a relay: a thyristor is able to close and open a circuit with powerful currents, receiving control commands using weak signals. The main design difference of thyristor stabilizers, which gives them an advantage over relay ones, is the absence of a contact group. This allows you to connect a fairly powerful load to such devices, the accuracy of their work is very high, and the noise during switching, unlike relay circuits, is practically absent. On the other hand, thyristors are sensitive to overheating and require the installation of active cooling systems (see below), which accordingly affects the price and dimensions of the device.

— Triac. Stabilizers built on triacs (symmetrical thyristors). In fact, they are a variety of the thyristor devices described above, and from the practical point of view, they do not noticeably differ from them in any way — neither in advantages nor in disadvantages.

— Electromechanical. The operation of such stabilizers is based on the operation of an electric motor (sometimes called a servomotor), which moves a special carbon contact directly along the transformer windings. Depending on the position of the contact, the number of turns of the winding included in the work changes; This is how the voltage is adjusted. Such models are considered one of the best in terms of price / quality ratio, they combine low cost with excellent accuracy and smoothness of adjustment. At the same time, the response speed in them directly depends on the degree of change in the input voltage: the stronger the jump, the greater the distance the brush must travel along the windings. Accordingly, electromechanical stabilizers are poorly suited to work with sharp drops in the network, and therefore, in order to avoid unpleasant consequences, the input voltage range (see below) is usually rather narrow. In addition, the brush is erased with constant movement, which requires periodic cleaning of the transformer and replacement of the brush itself; however, such a need does not arise often and usually does not cause difficulties. The operation of the servomotor creates some noise, but in general models of this type are quieter than relay ones (although noticeably louder than solid-state ones).

— ferroresonant. One of the first types of stabilizers mass-produced. The design of such a device is based on a pair of coils, reminiscent of a classic transformer. The characteristics of the coils are selected in such a way that when the input voltage is exceeded, the “extra” part of the magnetic flux from the input coil is diverted into the so-called magnetic shunt, and the magnetic flux through the output coil (and, accordingly, the voltage at its outputs) remained constant. Due to this, ferroresonance models have high speed and smooth operation, good accuracy, as well as a simple and inexpensive design. On the other hand, such stabilizers are not capable of delivering a smooth sinusoidal current, they are highly dependent on the frequency of the input current, they create noise on the line (which requires the use of filters when connecting sensitive electronics), they have a small range of input voltages and load powers (they are unable to operate idle or with overload). In addition, devices of this type are heavy and bulky. As a result, they are considered obsolete and are used relatively rarely.

— Combined. A kind of stabilizers that combines elements of relay and electromechanical models in the design. Usually, for small voltage surges, they use tuning with an electric motor; the relay, in turn, plays the role of insurance and is activated in case of significant deviations that the electromechanical part cannot cope with “alone”. Thanks to this, in one device it was possible to combine the advantages of both options — high tuning accuracy and a wide range of input voltages. However this type of stabilizer also inherited some disadvantages — in particular, the need to clean the brush and noise when the relay is triggered (although the latter happens less often than in purely relay models). In addition, the cost of such units is usually quite high.

— Double conversion. The principle of operation of this type of stabilizer is to convert AC to DC (using a rectifier) and then back to AC (using an inverter). The inverter is set up to provide a near reference voltage and a sine wave over the entire operating range of the input voltage. Thus, the main advantage of double conversion stabilizers is the high accuracy of the output signal, such devices are suitable even for delicate components such as TVs or speakers. In addition, the input voltage range turns out to be quite wide, the reaction to power surges is almost instantaneous, and due to the absence of moving parts, the stabilizer operates quietly and “lives” for a long time. The main disadvantages of such devices are high cost and relatively low efficiency (about 90%).

The maximum active load power allowed for this model.

Active power is the power that in AC appliances is spent on useful work or on heat generation. In addition to it, such devices also consume reactive power — it goes to the operation of specific components, primarily capacitors and inductors. Apparent power, denoted in volt-amperes (kilovolt-amperes), is the sum of active and reactive, see below about it. Here we note that in simple everyday situations, there is enough data on active power indicated in watts for calculations. In particular, it is this parameter that is considered the key when choosing stabilizers for washing machines and dishwashers : in the first case, power from 2 to 5 kW is considered optimal, in the second — from 1.8 to 2.5 kW.

Anyway, the total active power of the connected load should not exceed the figures indicated in the characteristics of the stabilizer. For a full guarantee, it's ok to take a certain margin, but this margin should not be too large — an increase in the allowable power significantly affects the dimensions, weight and price of the device. Also note that there are formulas that allow you to convert the active power consumption into total power, taking into account the type of connected electrical appliance; these formulas can be found in special sources.

Maximum apparent load power allowed for this model

In electrical engineering, full power is called, which takes into account both active and reactive power; the first type of power is discussed above, and the second can be described as the effect of windings, inductors and capacitors on the operation of AC networks. Apparent power is the main parameter for calculating loads on equipment in professional electrical engineering; it is usually denoted in volt-amperes (VA), in the case of stabilizers — in kilovolt-amperes (kVA). Note that for convenience, different types of power in electrical engineering are denoted by units with different names. That is why the power in W indicated in the characteristics of the stabilizer is usually not equal to its power in VA.

When choosing a stabilizer for some household appliances, it is quite enough to have active power data, but if possible it is better to use the full one. In particular, it is this parameter that is key when looking for a stabilizer for a refrigerator or a stabilizer for a boiler : in the first case, 0.4 – 1 kVA is considered the optimal value, in the second — from 0.1 to 0.7 kVA. However, anyway, it is necessary to choose a specific model in such a way that its total power is not lower than the total power of the entire connected load — and it is better to have a reserve (in case of unforeseen circumstances or connecting additional eq...uipment). At the same time, note that powerful models are distinguished by large dimensions and weight, and most importantly, high cost; therefore, it does not always make sense to chase the maximum numbers.

Also note that there are formulas that allow you to derive the optimal total power of the stabilizer based on data on active power and type of load; they can be found in special sources.

The voltage range at the input of the stabilizer, at which it is able to operate in normal mode and supply a constant voltage of 230 or 400 V to the load (depending on the number of phases, see above). The wider this range — the more versatile the device, the more serious power surges it can extinguish without going beyond the standard operating parameters. However, note that this parameter is not the only, and not even far from the main indicator of the quality of work: a lot also depends on the accuracy of the output voltage and the response speed (see both points below).

Also note that some models may have several modes of operation (for example, with 230 V, 230 V or 240 V output). In this case, the characteristics indicate the "general" input voltage range, from the smallest minimum to the largest maximum; the actual ranges for each particular mode will vary.

In addition, there are stabilizers that can operate outside the nominal input voltage range: with a slight deviation beyond its limits, the device provides relatively safe output indicators (also with some deviations from the nominal 230 or 400 V), but if the drop or rise becomes critical, it works appropriate protection (see below).

The largest deviation from the nominal output voltage (230 V or 400 V, depending on the number of phases), which the regulator allows when operating in the normal input voltage range (see above). The smaller this deviation, the more efficiently the device works, the more accurately it adapts to “changes in the situation” and the less voltage fluctuations the connected load is exposed to.

When choosing for this parameter, it is worth considering first of all how demanding the connected devices are for voltage stability. On the one hand, high stability is good for any device, on the other hand, it usually means a high price. Accordingly, it usually does not make sense to buy an advanced stabilizer for an unpretentious load like light bulbs and heaters, but for sensitive devices like audio systems or computers, it can be very useful.

The rate at which the regulator responds to changes in input voltage. It is determined by the time that passes from the moment of a power surge until the moment when the device fully adjusts to the new parameters and the output current corresponds to the standard 230 or 400 V (depending on the number of phases, see above). Accordingly, the shorter the response time, the better the stabilizer works, the lower the likelihood that a power surge will significantly affect the connected equipment. On the other hand, not all types of electrical appliances are sensitive to speed — for some, smooth adjustment or voltage accuracy is more important (see above); and the high speed itself can significantly affect the price of the device. Therefore, when choosing by this parameter, it makes sense to consider which devices are planned to be connected through the stabilizer.

— Wall mounted. This option includes two installation methods. The first, classic option is hanging with the help of “ears” on screws, studs or other similar devices. Thanks to this, the device does not take up space on the floor, in addition, the owner can choose the installation height; this is especially useful in cramped conditions. The disadvantage of this method, compared with the floor, can be called the need to "hollow the walls" and less suitability for moving from place to place; in addition, it is poorly suited for powerful heavy vehicles. The second type of wall-mounted devices are compact low-power models (usually a voltage relay — see "Device"), plugged into a socket not through a wire, but with a plug on the case itself. In fact, such a device is mounted directly on the outlet and does not require special installation.

— Outdoor. Floor models favorably differ from wall models in simplicity and ease of installation: in fact, apart from a flat surface, nothing else is needed for them. The role of such a surface can be played not only by the floor, but also by a shelf, countertop, etc. (the main thing is that such a design can withstand the weight of the stabilizer), and the installation itself is limited only to moving the stabilizer to the desired point in the room. In addition, the ease of moving from place to place is limited only by the mentioned weight, and it can be almost anything. Thanks to this, among the floor...models there are options for any available power and "tricks". The main disadvantage of this method is the need for space under the stabilizer on the floor or other surface.

Note that some models allow both wall and floor installation as standard. Such a device can be useful, for example, if you have not yet decided on a specific option, or if the situation can change at any time. In addition, it is technically possible to put the wall model on the floor, and equip the floor model with mounts and hang it on the wall, but usually such tricks at least do not make sense, or even lead to unpleasant consequences (such as overheating or breakage of the mounts).

The presence in the design of the stabilizer of a special handle for carrying the device from place to place. This feature is useful primarily for powerful and, accordingly, heavy devices, which would be inconvenient to hold directly by the case. And in the most "weighty" models, which are not designed to be carried alone, there are several handles.